Surface tension dialyzer element and method of constructing same



Jufly 3, 1934. L. CAMMEN SURFACE TENSION DIALYZER ELEMENT AND METHOD OFCONSTRU SAME Filed Dec. .10, 1932 INVENTOR ATTO RN EYS Patented July 3,1934 UNITED STATES SURFACE TENSION DIALYZER ELEMENT AND LIETHOD OFCONSTRUCTING SAME Leon Cammen, New York, N. Y., assignor to PrestonDavie, New York, N. Y.

Application December 10, 1932, Serial No. 646,733

2 Claims. (01. 210-169) This invention relates to improvements in themanufacture of a dialyzer element which is particularly adapted forsurface tension dialyzing liquid from commingled liquid, liquid fromcom- 5 mingled sludges, suspensions and the like, as generally describedin my copending application Serial No. 638,329 filed October 18, 1932.

The improved element structure, per se, is also adapted for other usessuch as a permeable l0 septum in filters.

In accordance with the invention, the element is preferably constructedof a continuous thin strip or" metal such as copper or brass or thelike, of substantially greater width than thickness. The flat surfacesof the thin metal strip are provided at equally spaced intervals, with aseries of fine transverse grooves, the alternately spaced grooved andungrooved areas on one fiat surface of the strip being staggered withrespect to the corresponding areas on the other fiat surface thereof.Thus the grooved areas on one surface of the strip are oppositelydisposed to the ungrooved area on the other surface thereof, etc. Theungrooved areas on each surface of the strip are also arranged so as tooverlap. Hence a short length of the strip on either surface at regularintervals, is entirely ungrooved.

The grooving of the surface of the strip just described, may beconveniently efiected by passing the strip between a pair of suitablyspaced cylindrical knurling rolls. Each of the rolls is so constructedthat a little less than one half of the periphery is uniformly knurled,and the remaining portion thereof is smooth. The rolls are so mountedthat the knurled periphery of one of the rolls is displaced angularlyapproximately 180, with respect to the knurled periphery of the other.Thus as the strip is fed between the rolls as they are rotatably driven,the strip will be grooved as explained above.

The alternately grooved and ungrooved strip so produced is then bent inzig-zag form fiatwise upon itself, the successive bends being made inopposite directions at the uniformly spaced ungrooved surface lengths,so that none of the grooves are deformed in the bending operation. Inthis way uniformly disposed and substantially identical foramina areformed between the contiguous grooved and ungrooved surfaces of theadjacent strips.

It will be understoodthat this method of construction readily lendsitself to the production of an element structure essentially rectangularin shape. It may then be clamped or otherwise mechanically secured inany convenient manner so as to permanently retain the contiguous layersin proper contact and to permanently maintain the completed element inrectangular form.

The completed structure may be generally described as a foraminouselement having a substantial but uniform thickness, and wherein a myriadof uniform and substantially identical macroscopic (in contradistinctionto microscopic) foramina provide a myriad of macroscopic continuouspassages of substantially greater length than the greatest dimension ofnormal cross section thereof.

As to dimensions, the knurling rolls are preferably so constructed as toproduce fine parallel grooves in the surfaces of the strip, whichgrooves in conjunction with the contiguous ungrooved (smooth) surfacesform the walls of foramina of the order of one hundredth (0.01) of aninch in their greatest dimension of cross section. The length of theforamina is largely determined by the width of the strip so that a widthshould be chosen of the order of four times, or more, the greatestdimension of cross section.

If the greatest dimension of cross section of the foramina normal to thelength thereof, is selected as five thousandths (0.005) of an inch orless (as the result of grooves produced by appropriately constructedrolls), the width of the strip should be selected so as to provide apassage length of not less than of the order of seven times the greatestdimension of cross section normal to the length thereof.

If the element structure is to be employed for surface tension dialysispurposes, as generally described in my copending application Serial No.638,329, filed October 18, 1932, the dimensions of the foramina shouldbe predetermined so that the regulated pressure to be applied bears adefinite relation both with respect to the surface tension of the liquidor liquids to be selectively recovered to the exclusion of otherscommingled therewith, and the dimensions as chosen.

If, however, the element is desired to be used, per se, as a permeableseptum for a given filtering operation, the dimensions of the foraminamay be predetermined without regard to the surface tension of thefiltrate and may, therefore, be chosen so that they are of a suitablesize to restrain solid particles of a given size. This use of theelement, per se, as a permeable septum for filtering purposes,contemplates as usual in the case of filter septums, the accumulation ofa shiny deposit on one surface of the element.

For a more complete understanding of the details of the elementstructure per se, and the method of constructing it, reference may behad to the following description considered with the accompanyingdrawing, in which Figure 1 illustrates in perspective a length of agrooved thin metal strip before bending;

Figure 2 illustrates the preferred manner of grooving both surfaces ofthe strip; and

Figure 3 illustrates a substantially completed foraminous element andthe manner of bending the strip to form the element.

In the drawing, 10 designates the prepared strip from which theforaminous element of this invention is constructed. This strip isformed of flat strip stock, designated 11 in Figure 2, of soft metalsuch as copper, brass, or other suitable material, of a width equal tothe required depth of the completed foraminous element, and of athickness to permit of ready bending, but sufficient to provide therequired crosssectiona1 dimensions of the foramina of the completedelement.

Both flat surfaces of the strip 10 are provided with spaced alternategrooved areas 12 and ungrooved areas 13. The grooved areas 12 on onesurface of the strip are displaced longitudinally with respect to thegrooved areas 12 on the other surface thereof, so that the grooved areas12 of opposite surfaces of the strip are staggered with respect'to eachother. In other words, an ungrooved area 13 on one surface of the striplies immediately above a grooved area 12 on the other surface of thestrip.

The ungrooved areas 13 on opposite surfaces of the strip overlapslightly so that short ungrooved lengths 14 on both surfaces of thestrip are formed adjacent the ends of each grooved area 12.

The individual grooves 15 of the grooved areas 12 are of such depth andshape as to form foramina of the desired dimension of normalcrosssection. To this end, the means which are used to form the grooves15 are shaped appropriately.

A convenient means for grooving the strip 10 in the required fashioncomprises a pair of rolls 16 and 1'7, shown in Figure 2. The axes ofthese rolls are parallel and the rolls are driven in opposite directionsas the strip stock 11 is fed therebetween, as shown in Figure 2. The'rolls are suitably spaced apart depending upon the thickness of thestrip stock 11 when between their smooth cylindrical surfaces 1.8, so asto continuously feed the strip therethrough without appreciable rollingof the strip to a lesser thickness.

Projecting radially beyond the smooth cylindrical portions of each ofthe rolls 16 and 17 are knurling teeth 19 of suitable size and shape toproduce the foramina-forming grooves 15 constituting the grooved areas12 of the strip 10. These teeth extend parallel to the axes of thecorresponding rolls and transversely of the strip stock 11 and occupyslightly less than 180 of the periphery of the respective rolls. Also,the toothed areas of the rolls are displaced angularly about 180 withrespect to each other so as to alternately groove the strip stock 11 asit is fed between them, whereby the grooved areas 12 thereof arestaggered with respect to each other.

Furthermore, because the grooved areas 19 of the rolls occupy less than180 of the respective peripheries of the rolls, the short ungroovedlength 14, on either surface, is formed adjacent the ends of eachgrooved area 12 of the strip 10. While the formation of the grooves bycoating rolls is a convenient and simple way of preparing the strip 10,it is described merely by way of illustration and it should beunderstood that any alternative method of grooving the strip may beemployed.

The grooved strip 10 is then bent zig-zag fashion fiatwise upon itselfby bending it in opposite directions at successive ungrooved areas 14,as illustrated in Figure 3. In this way the ungrooved areas 13 ei heroverlap or underlap the adjacent grooved areas 12, so that the flatsurface of each ungrooved area 13 closes the grooves 15 of the groovedarea 12 which it over-or-underlaps to form the foramina 20. Since theadjacent layers of grooved areas 12 and ungrooved areas 13 in thecompleted element 21 of Figure 3 are contiguous throughout, all of theforamina 20 thereof will beuniformly disposed and of substantiallyidentical cross section.

Inasmuch as the folds in the strip 10 are made at the ungrooved areas 14thereof, none of the grooves 15 are deformed. Furthermore, since thefolds are made in the ungrooved areas 14, which are thicker than thegrooved portions of the strip 10, the folds are strong and rigid andassist in maintaining the adjacent smooth and grooved layers of theelement in proper contact. Also, if the grooves 15 are formed in thestrip stock 11 by rolling in the manner described, the metal hardens toa certain extent, and if bent or folded at the thinned and hardenedportions where the grooves are located, is likely to crack. However, theprovision of the short ungrooved (smooth) lengths 14 in which the bendsare made, avoids this tendency, since the lengths 14 are thicker and aresubstantially unaffected by the grooving process and are thereforestronger and more malleable than the grooved areas.

It will be seen that the alternate layers of the finished foraminouselement 21, illustrated in Figure 3 are perfectly fiat with respect toeach other so that uniform contact is assured.

While the preferred form of element and the method of making itcontemplate grooves to be knurled in the surfaces of the strip stock,any equivalent thereof may be employed. It will also be obvious thatother changes may be made without departing from the scope of theinvention as defined by the claims.

I claim:

1. A foraminous element comprising a continuous strip of material foldedzigzag fiatwise upon itself to form superimposed layers, one of the twocontiguous surfaces between adjacent layers being grooved uniformly toform with the contiguous ungrooved flat surface a plurality of likeforamina extending through the element.

2. A foraminous element comprising a continuous thin strip of metal ofsubstantially greater width than thickness, each of the flat surfaces ofthe strip being provided at equally spaced intervals with a series offine transverse grooves, the alternately spaced grooved and ungroovedareas of one fiat surface being staggered with respect to thecorresponding areas on the other fiat surface thereof, and ungroovedareas on each .flat surface at regular intervals, said strip beingfolded zigzag fiatwise upon itself at the regularly spaced ungroovedintervals, the contiguous grooved and ungrooved surfaces forming amyriad of like foramina extending through the element.

LEON CANDMIEN.

